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. H. SAURER. I APPARATUS FOR TESTING THE TEETH OF GEAR WHEELS.APPLICATION FILED APR. 10, 1920.

Reissud Dec. 21, 1920.

' 2 SHEETSSHEET I.

H. SAURER.

APPARATUS FOR TESTING THE TEETH 0F GEAR WHEELS.

APPLICATION FILED APR. 10, I920.

Reissued Dec. 21, 1920. i 1 5 ,0 1 3 2 SHEETS-SHEET 2- sirable results.

UNITED STATES PATENTTLTIOFFICEE.

HIIPPOIiYT SAURER, OF ARIBON, SWITZERLAND.

APPARATUS FOR TESTING THE TEETH GEAR-WHEELS.

' To all whom may concern Be it known that I, HIPPOLYT SAURER, a cltizenof Switzerland, residing at Arbon,

Switzerland, have invented new and useful Improvements in Apparatus forTesting the Teeth of Gear-Wheels, of which the followin is aspecification.

yinvention relates to improvements. in apparatus for testing the teethof gear wheels whereby the inaccuracies of the working faces of theteeth are indicated. If the teeth of one or both of a pair ofintermeshing gears be inaccurately formed, one of the pair, for instancethe driving gear, may be turned at any desired speed while the other,namely the driven gear, will have an irregular or jerky movementincluding successive accelerations and retardations in respect to thespeed of the driving gear, as successive teeth come into or pass out ofmesh. These comparatively slight speed variations of the driven gearabove and be low the mean or average speed determined 'by the speed ofthe driving gear and the relative pitch diameters. cause noise, excesssive wear, frlction losses and other; unde- The object of my inventionis to provide an apparatus in which commercially made pairs of gears ofvarious different sizes and relative pitch diameters may be inserted andtested and'the ordinarily comparatively I slight inaccuracies be clearlyshown and recorded on a greatly enlarged scale.

In carrying out my invention I provide an indicating member, preferablyin the form of a stylus or other recording member movable in respect totwo separate axes, and control its movement by two coaxial rotatablecontrolling members having separate driving connections from theseparate gearsto be tested. The driving mechanism includesinterchangeable part or parts so designed that'the coaxial controllingmembers for the stylus may be rotated at approximately the same speedeven though the gears being tested have different pitch diameters andtherefore rotate at different speeds.- Thus for perfectly formed teeththe two members may rotate at approximately the same uniform speed andthe stylus will move in respect to only one of its axes and trace asmooth curve. ariations in the relative rates of rotation of the gearsdue to gear teeth inaccuracies orother cause will eration andretardation Specification of Reissued Letters Patent. Reissued B a 211920 Original'No. 1,263,472, dated April 23, 1918, Serial No. 33,?06,filed June issue filed A ril 10, 1920. Serial No. 372,983.

12, 1915. Application for regive to the stylus a secondary movementabout its other axis due to alternate accelof the driven gear and itsstylus controller.

As a preferred embodiment and as an lmportant structural feature I mountthe two coaxial stylus controlling members 00- axial with the supportfor oneof the gears to be tested. This. permits one to be rigidlyconnected to one gear support. Motion is transmitted to the other styluscontrolling member from the other gear support by a suitable pair ofdisks, the diameters of which may be in the same ratio as, the diamseters of the'pitch circles of the gears to be tested.-. Preferably theyhave the same diaineters as said pitch circles and are mounted coaxialwith the gears with their peripheries in frictional driving engagement,one disk beingrigid with its corresponding gear and stylus controllerand the other disk being rigidlyconnected to the other styluscontrolling member but loose in respect of the gear coaxial therewith.Thus as the, gears rotate, motion will bedirectly communicated to onestylus controlling member fromthe gear coaxial therewith and motion willbe communicated to the other stylus controlling member. from the othergear. through the friction disks. Any tooth inaccuracy causing relativespeed variation .of one of the gear wheels therefore causes anirregular, zig-zag or secondary movement o fthe stylus which may beeasily noted and recorded.

For the purpose ofexplaining the invention an example embodying the samehas been shown in the accompanying drawing, in which Figure 1 is avertical cross-section of the apparatus with a pair of gear wheelsmounted thereon. Fig. 2 is a side elevation partly in section, therecording mechanism eing omitted. Fig. 3 is a detail sectional view ofthe spindle bearing, and Fig. 4 is a view of a record made by the use ofthe ap aratus.

n theexample shown in the drawing my improved apparatus includes a pairof spindles, 1 and 2 which are mounted on a common frame .or bed 21 soas to be shiftable relative toward and from each other but preferablyheld against rotation. The particular means employed for effecting therelative adjustment of the spindles is comparatively unimportant but isshown as including slides 22, both of which are shiftable in a suitableguide-way 23 formed on the bed 21. The two spindles are carried by thetwo slides and the latter are adapted to be moved toward and away fromeach other by means of a screw threaded spindle 24 mounted in a bracketon the bed and having a crank 25.

I On the spindle 1 there is rotatably mountposed between these parts.Encirclmg the I I sleeve-1 is a second sleeve 11, the two sleeves beingprovided with an interposed ball bearingl 10. The two sleeves 3 and 11constitute t I to be tested. I have shown apair of gears and atapproximately the same speed as the,

6 and 9 detachabl secured to these sleeves, the two spindles eingadjusted in respect to each other so that the gears properly.

mesh. I

For rotating the sleeve 7 from the gear 6 sleeve 11 which carries thegear 9 I provide a pair of disks .5 and. 8. These are preferablyfriction disks having their petwo disks being removable an of the samepitch diameters as the gears to be tested and held co-axial with thegears. The disk 5 is shown as rigidly but detachably secured to thesleeve 3, while the disk 8 is shown as rigidly but detachablysecured1to' the sleeve I I The two co-axial sleeves 7 and 11 constitute partsof or serve to carry two controling members for the indicating member.In

the specificv form illustrated the upper end of the sleeve 7 has acasing ri 'dly secured thereto and rotatable therewit The casing,adjacent to the peripheral wall thereof,

has a pivot bolt 14 parallel to the spindle 2 and serving asa pivot'f'oran arm 15 extending across the casing. This arm termis nates ina segment16 provided with ear teeth meshing with a pinion 17 carried y a pivotmember 28 mountedin the casing and.

also parallel to the spindle.- This pivot member has rigidly connectedthereto an arm 18.carryin at its end a stylus 26 which serves as an in'icating member, it being so mounted as to trace indications on a recordblank 19.. This record blank is shown as non-rotatably'secured'to theupper end of the fixed spindle 2. To the upper end of the sleeve 11there is keyed an arm 12'which I is provided at its outer end with 'afinger 13 engaging in the bifurcated part 27 of the arm 15 whichprojects-through a slot in the wall of the casing 20. I

The operation of he apparatus is as follows:

The pair of gear wheels 6 and 9 to be tested are'rigidly secured to the"sleeves 3 and 11. Friction disks 5 and 8 having the "6 and 9 will be inproper mesh. The

Rotatably wheel 6, its supporting sleeve 3 and the rice supports for thepair of gears the two co-axial sleeves -7 and 11.

same diameters as the pitch diameters of the ar wheels are secured tothe sleeves 3- and 7. The spindles are then brought to the properadjustment by means of the screw threaded spindle 24. The friction disks5 and 8 will then be in direct driving engagement with each other andthe gears e'ar tion disk 5 are then slowly rotated in any suitablemanner as, for.instance, by hand.

- tion disk 8 are exactly alike and there is,

therefore, 110 relative rotary movement of The casing'2O and the arm 12which control the movement, of the stylus rotate together and there isno relative. movement of the segment 16 and pinion 17, and the stylusfollows a direct path and draws a circle on the of the ears areincorrect, the uniform rotation 0 the gear wheel 6 will, impart non- Iuniform or irregular movements to the gear wheel 9. As t friction disk8., sleeve 7 and casing 20 are rotatedby the gear 6, and the arm 12 isrotated by the gear 9, the non-uniform movement of the gear 9 in re-Spect to thegear 6 will cause slight relative rotary movements of thearm 12 and the casing 20 and, therefore, the stylus 26 will be caused tomove not only in a circular.

patharound the spindle 2 but also in a curved path about the pivotmember 28. Any slight accelerations and retardations of the gear 9 inrespect to the gear 6 will cause oscillations or back and forth movevments of the stylus. This oscillatory or back and forth movement of thestylus about the pivot member 28 will be recorded on the record blank 19as a zig-zag line.

'In Fi 4 I have shown a record blank with such a zig-zag line thereon asmay be produced by irregularity in the shape of I the .gear t'eethfaces. If the relative diameters of the disks and the" ears be exactlythe same, the line, after a single rotation of the gear 9, willcome backto the starting point. If there be a very slight difference in therelative pitch diameters of the disks and the gears, the spiralwillresult as shown in Fig. 4.

In descrlbing the invention referencgjilhas been made to an example inwhich'th'friction disks are mounted concentrically of the correspondinggear wheels. While I preferthis construction by reason of its sim-,

plicity and the exact operation, I wish it to be understood thatmylinvention isnot lim-. I

ited to this feature, and that various record blank 19. ,If thesaid'working faces ripheries in directdriving en agement, the

I changes may be made in the general arrangement of the apparatus andthe construction of its parts within the glst of my invention.

I claim herein as my invention:

1. In an apparatus for testing pairs ofgear wheels, the combination witha pair of supports for said gear wheels for rotation thereof inengagement with each other, of a pair of friction disks the diameters ofwhich are of the same ratio as the diameters of the pitch lines of thegear wheels and adapted for correct driving engagement with each otherand one connected with one of the gear wheels for rotation in harmonytherewith and the other one loose relatively to the other gear wheel,means to shift one of said supports to bring disks of different sizeinto driving enga ement, "and means to record the relative splacementsof the disk and gear wheel which are loosely mounted relatively toeachother.

2. In an apparatus for testing pairs of gear wheels, the combinationwith a pair of supports for said gear wheels for rotation thereof inengagement with each other, of a pair of friction disks the diameters ofwhich are respectively the same as those of the pitch lines of the gearwheels andadapted for correct driving engagement with each other and oneconnected with one of the gear wheels for rotation in harmony therewithand the other one loose relatively to the 1 other gear .wheel, means toshift one of said supports to bring disks of different size into drlvlngengagement, and means torecord the relative displacements of the, diskand gear wheel which are loosely mounted relatively to each other. v

3. In an apparatus for testing pairs of gear wheels, the combinationwith afpair of supports for said gear wheels for rotation thereof inengagement with each other, of a pair of friction disks the diameters ofwhich are respectively the same as those of the pitch lines of the gearwheels and incorrect driving engagement with each other and mountedrespectively coaxially of the corresponding gear wheels and oneconnected with one of the gear wheels for rotation in harmony therewithand the other one loose relatively to the other. gear wheel, means toshift one of said supports to bring disks of different size into drivingengagement, and means to record the relative displacements of the diskand gear wheel which are loosely mounted relatively to each other.

4. In an apparatus for testing pairs of gear wheels, the combinationwith a pair of supports for said gear wheels for rotation thereof inengagement with each other, of a pair of disks the.diameters of whichare of the same ratio as the diameters of the pitch lines of the gearwheels and adapted for correct driving engagement with each other andoneconnected with one of the gear wheels for rotation in harmonytherewith and the other one loose re'Iatively to the other gear wheel,means to' shift said gear wheels and disks into engagement with eachother, and means to ascertain the relative displacements of the disk andgear wheel which are loosely mounted relatively to each other.' 1 r 5.In an apparatus for testing the working faces of pairs of gear wheels,thecombination with a pair of rotary members, and a sleeve rotatablymounted concentrically of one of said members, the other of said rotarymembers and the sleeve being adapted to have the gear wheels to betested secured thereto in position for engagement with each other, of apair of friction disks the diameters of-which correspond respectively tothe diameters of the pitch lines of the gear wheels and securedrespectively to the rothe corresponding gear wheels, and means toascertain the relative displacements of the gear wheel which is mountedon the sleeve and the friction disk which is mounted on the concentricrotary member.-

6. In an apparatus for testing the working faces of pairs of gearwheels, the combination with a pair of rotary members, and a sleeverotatably mounted concentrically of one of said members, the other ofsaid rotarymembers and the sleeve being adapted to have the gear wheelsto be tested secured thereto in position for engagement with each other,of a pair of friction disks the diameters of which correspondrespectively to the diameters of the pitch lines of the gear wheels andsecured respectively to the rotary supports concentrically respectivelyof the corresponding gear wheels, a casing and an operating arm takingpart respectively in the rotation of the'sleeve and the support which isconcentric thereof, and a rocking indicating member mounted on saidcasing and engage by said arm.

In an apparatus for testing the working faces of pairs of gear wheels.the combination with a pair of rotarv members adapted to have the gearwheels to be tested secured thereto in position for proper meshingengagement with each other, of a support and an operating arm rotatableabout the same axis, a rocking indicating member mounted on sald supportand engaged v by saidarm, means for rotating said support from one ofsaid gears, and means for rotating said operating arm from the other ofsaid gears and at approximately the same speed as the speed of rotationof the casing.

8. In an apparatus for testing the working faces of pairs of gearwheels, the combination with a pair of rotary members adapted to havethe gear wheels to be tested detachably secured thereto in position formeshing engagement with each other, of an indicating member mounted formovement about two independent'axes, and a pair of rotatable co-axialcontrollers for said indlcating member, one of said controllers beingdriven by 'one of said rotary members and e the other of saidcontrollers being driven by the other member at approximately the samespeed whereby uniform rotation of 4 said gears and controllers eflectsmovement of said indicating member about one of its axes and non-uniformrotation of said gears and controllers efi'ects movement of saidindicating member about both of its axes.

- 9. In .an apparatus for testing pairs of gear wheels, the combinationwith a pair of .members forsupporting gear wheels to be tested, of meansto effect a relative movement of said members toward and from each othertobring gears of different sizes into driving engagement, a stationaryrecord blank support, a stylus, driving connections between said stylusand one of said members for moving said stylus in respect to the axis ofsaid'record blank, and'means connecting said stylus with the other gearsupport for imparting a secondary movement to the stylus upon 'relativerotary movements of said supports other than uniform movements at. ratesinversely proportional to the diameters of thepitch lines of the gearsto be tested.

10. In an apparatus for testing pairs of gears whee1s,"thecombinationwith a pair of supports for said gear wheels forrotation of the latterinmes ing engagement, of a stationary record blank, a stylus carryingmember rotated by one of said supports and a member rotated by the otherof said supports at approximately the same speed as said first mentionedmember and engaging with said stylus to move the latter in respect tothe first mentioned member upon a variation in the relative rates ofrotation of said gear and their supports.

11. In an apparatus for testin the working faces of pairs 'of-gear whees, the combination with a pair of rotary members adapted to have thegear wheels to be tested secured thereto, a record blank co-axial withoneflof said members, a stylus, a carrier therefor secured to one ofsaid supports and means driven by'the other support and rotatable withsaid stylus carrier for eifecting a movement of the stylus in respect toits carrier upon accelerations or retardations of the speed of onesupport in respect to the speed ofthe other.

nation of means to support rotatively and in mesh the gears to betested, a pair of rotating members mounted coaxially, one' 13. In a geartesting machine, the combination of means to support rotatively and inmesh the gears to be tested, a pair of rotating members mountedcoaxially, one rigid with one gear and the other driven from the othergear, and an indicating mechanism carried by one of said members andinfluenced by the other.

' 14. In a gear testing machine, the combi- -/nation of means to supportrotatively and in mesh the gears to be tested, a pair of rotatingmembers mounted coaxially, one rotated in harmony with one gear and theother driven from'the other gear at approximately the same speed as thatat which said members and influenced by the other.

15. In a gear testing machine, the combination of means to supportrotatively and in'mesh the gears to be tested, a pair of ro-.

tating members mounted coaxially, one rotated in harmon with one gear,driving means between t eother member and the 1 other gear and includinga pair of disks having diameters of the same ratio as those of the pitchcircles of the ears, and an indicating mechanism having diflerentmovements produced by constant or varying relative movements of saidmembers.

Signed at St. Gall, Switzerland, this 12m day of March, 1920.

HIPPOLYT SAURER.

12. In a gear testing machine, the combi-

